DSLR's and planet imaging

[skfboiler]

I've been hearing DSLR's are not the greatest when it comes to imaging planets. What specifically make DSLR's bad planet imagers?

[brantuk]

It's not that dslrs are bad - just inappropriate. If you could stand on the edge of the atmosphere with a dlsr and a zoom lense you'd get some smashing shots of planets cos it would be constantly clear.

But us mere mortals are stuck with standing on the ground and looking through the astmosphere with our cameras. Moments of perfect atmospheric clarity are rare as the planets appear to wobble and get get "jiggled" about in the eyepiece by air currents, temperature hazes, and pressure movements. In a scope these are magnified and it's hard to pick the right moment to click. Even on a good clear night it's difficult to get a perfect shot.

So it's much better to have a film rolling gathering frames at a rapid rate - gives you much more chance of finding a decent shot - and you can discard the not so good frames leaving only good ones to stack and align. Hope that clarifies it for you

[Sam]

It's basically because a webcam gives a much better result. A DSLR will take one image or a bunch if you set it up to do a run but a webcam can do many thousands in an uncompressed avi format that can then be stacked and the bad frames thrown out. To do the same on a DSLR you'd get a sore finger or a worn out mechanism in the camera very quickly. The DSLRs that can take movies are heading in the right direction but I'm not sure they take uncompressed frames. Does that help?

[skfboiler]

Thanks for the replies.

What if I use the video feature of the DSLR camera and capture 3 to 5 minutes of data? I think it saves the movie as a .mov file. With a file conversion program, convert it to an .avi file so Registax can read it and then process the image there. Will that be similar to using a webcam? What i'm trying to do is 1) use 1 device to capture images of planets and DSO's. and 2) I'm trying not to bring a laptop onsite if I don't have to. If the DSLR video feature is still not good for planets, then I will look into the Orion StarShoot Deep Space Video Camera for both planets and DSO's with one device. I'll still need a laptop onsite though. Or connect to a camcorder, TV etc.

[Sam]

That would work but the problem is that the original frames taken by the camera have been compressed into to the first format so you've lost some data by the time you get it to an avi.

[Bizibilder]

You could try EOS Camera Movie Record, which is freeware:

EOS Camera Movie Record | Download EOS Camera Movie Record software for free at SourceForge.net

This works with the Canon range of DSLR's and takes .avi's using the cameras liveview function - I've used it a few times and it certainly does work on the Moon so I see no reason why it shouldn't work on Planets too.

[Mike Hackenbacker]

i still use my compact camera for filming moon or the planets,then try to clean em up with my movie editor,i use u-lead 11 plus,as it can handle HD files although i have not filmed in HD,that is only available on my video camera,shooting the movie in avi takes up more memory but its better than Mpeg or WMV,i have still yet to learn how to use registax so the footage i have on youtube is just the raw movie edited before posting.

[Superewza]

So... why not just use a DSLR's video functionality?

[jaffons]

hmm.

I thought that webcams sensors are the lowest quality and therefor not so good? Or is the bad link just the plastic lens in front of cam?

[Superewza]

hmm.

I thought that webcams sensors are the lowest quality and therefor not so good? Or is the bad link just the plastic lens in front of cam?

Well a rule of thumb practically as old as photography itself is that as you increase the size of the recording medium the quality of the image increases exponentially. So tiny phone cam sensors, then webcam and compact digital camera sensors, then DSLR sensors, then 35mm film, them Medium Format film, and then the holy grail... large format and beyond

[Cornelius Varley]

hmm.

I thought that webcams sensors are the lowest quality and therefor not so good? Or is the bad link just the plastic lens in front of cam?

The reason why webcams and similar (Imaging Source, Lumenera etc) are better than DSLRs is because they can can capture a large number of images in a short period of time. The AVI file is then processed in Registax/Avistack to improve the signal to noise ratio, the final image being vastly better than a single frame. DSLRs have a larger sensor than webcams but, for planetary imaging, this size is inefficient. The bigger / higher resolution sensor of a DSLR doesn't produce a better image than a 640x480 webcam or Imaging Source D*k 21 because the diameter of the planet on the sensor is the same for both types of camera for the same focal length.

I am not sure what you mean by "webcams have the lowest quality sensor". The Philips Toucam Pro II/ SPC880 / 900 uses the same sensor as found in the Imaging Source D*K21.AU04.AS cameras and they are well regarded. Remove the lens from a Toucam and replace it with a 1.25" adapter and the image quality will be close to the I.S. cameras. The adavantage of the I.S. camera is that it has a better frame rate than a webcam.

Peter

[JoLo]

Yes, DSLRs have issues with planetary imaging and webcams are the superior choice for all the reasons stated above. However, with a little patience, lots of subs, and Registax, you can really get some decent planetary images with a DSLR. It all comes down to seeing on any given night, and timing. If you capture a few shots when the transperancy is good and the image is clear, Registax will get you a decent image.

[Sam Baker]

I have a slight problem with using my dslr and stacking the images - I use an intervalometer so I can take photos literally as quick as the camera will and I change a few settings along the way however out of the 476 photos I took yesterday at 85 percent quality on registax only 2 of them would fit - I don't really understand where I'm going wrong here - so I manually aligned every image and ended up with which I personally think isn't bad - rather than individually snapping images and taking a videoninstead then converting the frames to avi would I really achieve such a good quality image that will align automatically without me having to go bog eyed for an hour?

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[PeterCPC]

Personally I am getting better results using my Canon 550d with Backyard EOS than with my Image Source camera. I use a Barlow with the Canon and take AVIs which I then stack in Registax after running them through PIPP. This is Jupiter taken a few nights ago. BYE also gives you a 5x or 10x digital zoom facility - this image was taken using the 5x zoom with a 3x Barlow lens. I find the Canon so much easier to use with BYE than using my DFK21.

Peter

[rustigsmed]

planets require as much resolution as possible, a high frame rate and low noise, this is where mono planetary cameras come into their own and beat the pack.

most new DSLRs will do 30fps with some doing 60fps at 720p. this still enables good results if the seeing is good and its not too hot out. von Tom on flickr comes to mind

Great huh? I have exactly the same setup as vonTom https://www.flickr.com/photos/vontom/with/5334416773/  but don't achieve anywhere near that quality of picture, probably more consistent seeing and better processing skills are the difference.

for a good planetary camera though you don't need to spend a fortune consider the ZWO ASI120MM, you will need to get the filter wheel as well but it produces fantastic planetary pictures at what is a really cheap price.

[happy-kat]

Thought it was also to do with the ratio of image size to the sensor, much better on the Web cam so bigger image using more pixels.

http://stargazerslounge.com/topic/208610-planetary-imaging-with-dslr-video-mode/?fromsearch=1

[jambouk]

My revised understanding of why dslr's are not as good as "webcams" is do do with the compression; they appear to compress the data more before saving it than the webcams do (probably related to the fact the sensor is so much larger and there is so much data to write to the memory card. I hear backyard eos and the like allow users to zoom in using the dslr and potentially just record the data ffrom a smaller area of the chip (without binning pixels) which may mean less compression and therefore better overall resolution. I've yet to hear if this is the case or not, but if it is, then dslr cameras may be comparable to planetary cameras depending on the maximum frame rates achievable.

Jd

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